Tasselled Wobbegong: Eucrossorhinus dasypogon

Family: Orectolobidae
Common name(s)

Tasselled Wobbegong.

Identification

Laterally depressed (flattened) body. Extremely wide head with a complex arrangement of branching skin flaps that form a beard-like, unbroken fringe that continues to the origins of the pectoral fins. Pectoral and pelvic fins very large and rounded.  Two large similarly sized dorsal fins with rounded tips, set far back on body. Origin of first dorsal level with pelvic fin insertion.
Dorsal pattern composed of intricate light and dark spots (often containing many tiny pale flecks) over a brown, grey, and beige background. Spots usually form dark saddles along midline. Markings may be pale and/or indistinct on some animals.

Size

Maximum length 125cm. One record of a 366cm specimen is almost certainly a misidentification. Size at birth approximately 20cm.

Habitat

Tropical coral reefs and rocky reefs, sand flats adjacent to reefs, and caves. From shallow bays to 50m or more.

Distribution

The tasselled wobbegong is common in New Guinea from Raja Ampat to PNG, and from Ningaloo Reef in northern Western Australia, around the north coast of Australia to Bundaberg in southern Queensland.

Conservation Status

LEAST CONCERN

Threats within Australia are likely to be minimal, as the species is not commercially or recreationally targeted and is rarely caught as bycatch. It has refuge outside of trawled areas due to its association with coral reefs. The Tasselled Wobbegong was observed in the bycatch survey of the Pilbara Trawl Fishery (Department of Fisheries WA 2010), but catch rate was not reported and is likely to be low due to trawling not taking place in its preferred reef habitat. The species has not been reported in the Coral Reef Line Fishery or the East Coast Inshore Fish Fishery. It is an occasional bycatch in the Queensland East Coast Trawl Fishery (Kyne 2008).

The number of wobbegongs caught by recreational fishing from boat licence holders in Western Australia during 2011-12 was estimated at 1,535 animals, with 20% retained (304) and 5% caught from the North Coast region (Ryan et al. 2013), resulting in ~15 wobbegongs caught annually within the distribution of the Tasselled Wobbegong (where several wobbegong species occur)

Outside of Australian waters, wobbegong species are not targeted, but could potentially be caught in the Gulf of Papua prawn trawl fishery, particularly if trawling occurs near coral reefs (L. Baje, pers. comm., February 2015). The Tasselled Wobbegong might also be threatened locally by habitat destruction from dynamite fishing, especially in Biak, West Papua.

Citations and References
Huveneers, C. & Pillans, R.D. 2015. Eucrossorhinus dasypogonThe IUCN Red List of Threatened Species 2015: e.T41873A68623121. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T41873A68623121.en. Downloaded on 31 December 2020.

Reproduction

Ovoviparous. Presumed lecithotrophic, i.e. the foetus is solely nourished by the yolk within the egg case.

Diet

Feeds on small fishes that it ambushes by remaining motionless while camouflaged against the reef. When an appropriately sized fish swims in front of its disguised mouth, the wobbegong lunges forward simultaneously stretching its mouth open. The process sucks water and fish into its maw, which immediately snaps shut again, piercing its prey with needle-like teeth.

Behavior

Nocturnal. Rests by day (often with its tail curled in a spiral) under shaded reef ledges or in caves. The tasselled wobbegong’s range is generally quite small. Based on personal observations of tasselled wobbegongs that seemed to be in exactly the same spot on numerous dives,  it is possible that this species remains motionless for multiple days.

Reaction to divers

Very easy to approach. Tasselled wobbegongs occasionally bolt if approached too quickly or if they are out in the open, but they are more likely to remain motionless, relying on the excellent camouflage.

Diving logistics

Tasselled wobbegongs are easily located at numerous dive sites throughout Raja Ampat in Indonesia. At many sites, it is not uncommon to see fur or five on a single dive.

Triton Bay on the south coast of West Papua is another good spot in Indonesia for this species.

In Western Australia, the best place to find them is under the navy pier at Exmouth. They are also sighted regularly further offshore at Ningaloo Reef.

Sightings on the Great Barrier Reef are also commonplace. Two spots where tasselled wobbegongs are very common are Heron Island and Lady Elliott Island.

Similar species

Other Wobbegongs All other wobbegong species have proportionately narrower bodies and less dermal lobes around their mouths. Their dermal lobes are also much simpler/ less branched.